Pteridine derivatives and method

ABSTRACT

A COMPOUND 2-AMINO-4-HYDROXY-6-HYDROXYMETHYL-7,77DIMETHYL-7,8-DIHYDROPTERIDNE, OR TAUTOMERIC FORMS THEREOF AND PHARMACEUTICALLY ACCEPABLE SALTS THEREOF. THE COMPOUNDS IS USEFUL AS A BACRERIOSTAT AND IN ANTIBACTERIAL PRODUCTS. THE COMPOUND HAS USEFUL ACTIVITY AGAINST CL. PERIFRINGENS AND DERM, DERMATONAMOUS.

' United States Patent Office 3,801,643 Patented Apr. 2, 1974 US. Cl.260-584 A 3 Claims ABSTRACT OF THE DISCLOSURE A compound2-amino-4-hydroxy-6-hydroxymethyl-7,7- dimethyl-7,S-dihydropteridine, ortautomeric forms thereof and pharmaceutically acceptable salts thereof.The compound is useful as a bacteriostat and in antibacterial products.The compound has useful activity against Cl. perfringens and Derm.dermatonomous.

This is a division, of application Ser. No. 160,216, filed on July 6,1971 now US. Patent 3,725,408 which is a division of application Ser.No. 794,786 filed Jan. 28, 1969 now US. Pat. No. 3,635,978.

The invention described herein was made in the course of work under agrant or award from the department of Health, Education, and Welfare.

DESCRIPTION OF THE INVENTION The present invention relates to aderivative of pteridine.

It has beenfound that the compound 2-amino4-hydroxy 6 hydroxymethyl 7,7dimethyl-7,8-dihydropteridine (Formula I, cols. 4-6 hereof), ortautomeric forms thereof, and pharmaceutically acceptable salts thereofare useful as bacteriostats. The above mentioned compound, or tautomericforms thereof and pharmaceutically acceptable salts thereof are ofparticular value in anti-bacterial products effective against thefollowing organisms: Cl. perfringens and Derm. dermatonm mous.

The compound 2-amin0-4-hydroxy-6-hydroxymethyl-7,7-dimethyl-7,S-dihydropteridine, or tautomeric forms thereof, and saltsthereof are useful in solution to sterilize medical instruments.

The Compound I may be prepared by the synthetic route shown in the flowchart in cols. 4-6 hereof.

It is assumed that the intermediate Compound X is formed; the conversionof Compound IX to Compound I is carried out in practice by the reductivecyclization of the former by reducing agents capable of reducing thenitro group without attacking other parts of the molecule, for example,by means of sodium dithionite or catalytic hydrogenation using catalystssuch as palladium charcoal, platinum or Raney nickel.

The reagents and reaction conditions preferably used in the stepsoutlined in the flow chart will appear from the following example andmay be modified in any manner as will be apparent to those skilled inthe art.

According to the present invention, therefore, there are provided:

(i) The compound 2 amino4-hydroxy-6-hydroxymethyl-7,7-dimethyl-7,8-dihydropteridine (I),tautomeric forms and salts thereof:

(ii) The method of preparing (I) which comprises the reductivecyclization of 2-amino-4-(1,'1-dimethyl-3-hydroxy-acetonyl)amino-6-hydroxy-S-nitropyrimidine (IX), for example, with sodium dithionite;

(iii) The compound I when prepared by the method (ii); and

(iv) As novel compounds of value as chemical intermediates:

(a) 1-diazo-3-methyl-B-phthalimidobutan-Z-one (IV);

(b) 1 hydroxy-3-methyl-3-phthalimidobutan-2-one (V);

(c) 3 amino-l-hydroxy-3-methylbutan-2-one (VI) and salts thereof;

(d) 3 amino 1 hydroxy-3-methylbutan-2-one semicarbazone (VII) and saltsthereof;

(e) 2 amino 4 (1,1'-dimethyl-3'-hydroxyacetonyl) amino 6hydroxy-S-nitropyrimidine semicarbazone (VIII); and

(f) 2 amino 4 (1',l-dimethyl-3-hydroxyacetonyl)amino-6-hydroxy-5-nitropyrimidine (IX).

If a salt of the Compound I is used the salt should be a salt of apharmaccutically acceptable acid or alkali, such as hydrochloric acid,sulphuric acid, tartaric acid, maleic acid, ammonia, sodium-hydroxideand tetramethylammonium hydroxide. 'Ihe Compound I may be used as abacteriostat in a concentration of to mg./ml. of the solution in whichthe organism is capable of growing without the compound.

The invention, in another aspect, provides pharmaceutical formulationscomprising the Compound I, or tautomeric forms thereof, orpharmaceutically acceptable salts thereof, in association with apharmaceutically acceptable carrier. The substance may advantageously bepresented in discrete units, such as tablets, capsules, cashets orampoules, each containing a predetermined amount of the compound. It mayalso be presented as a powder or granules as a solution or suspension inan aqueous, nonaqueous or emulsified liquid, or as an ointment. Forparenteral use, the formulations must be sterile and are presented insealed containers. The formulations of this invention may be made by anyof the methods of pharmacy, and may include one or more of the followingaccessory ingredients; diluents, solutes, buffers, flavoring, binding,dispersing, surface-active, thickening, lubricating and coatingmaterials preservatives, antioxidants, and ointment bases and any otheracceptable excipients.

The following example illustrates the invention. Temperatures are indegrees Celsius.

Example N-phthalyl-2-aminoisobutyric acid (II).A mixture of phthalicanhydride (80 g.) and 2-aminoisobutyric acid (40 g.) was fused at180485". The temperature was maintained at for 20 minutes and the meltallowed to cool overnight. It was dissolved in 10% sodium bicarbonate(-1 litre), filtered and acidified with concentrated hydrochloric acid.The mixture was cooled and the white crystalline solid was filtered,washed with water and dried (60 C.), M.P.153-'154.

N-phthalyl-Z-aminoisobutyric acid chloride (III).-N-phthaIyl-Z-aminoisobutyric acid (75 g.) was treated with thionylchloride (200 ml.) under reflux for 1 hour.

Thionyl chloride was evaporated in vacuo, followed by three evaporationswith ether to remove residual traces. The residue was recrystallizedfrom petroleum ether (60- 80) to give a colorless crystalline solid,M.P. 79.

1 diazo 3 methyl 3 phthalimidobutan-Z-one (IV).-An alcohol-free etherealsolution of diazomethane was prepared by adding Diazald (136 g.)dissolved in ether (950 ml.) dropwise to a flask containing a solutionof potassium hydroxide (40.9 g.) in water (70 ml.), ethyl digol (240ml.), and ether (70 ml.), heated on a water bath at 6570. Thediazomethane formed in situ was distilled and collected. To this asolution of N-phtha1yl-2- aminoisobutyric acid chloride (51.1 g.) inether (700 ml.) was added slowly with shaking. The mixture was leftovernight at room temperature. The ether was evaporated in vacuo to givea pale yellow crystalline solid. This material was pure enough to beused in the next reaction.

1 hydroxy 3 methyl-3-phthalimidobutane-2-one (V).The diazoketone (50 g.)prepared above was suspended in 0.5 N-sulphuric acid (500 ml.) andwarmed to 80 to initiate hydrolysis. After all effervescence had ceased,the mixture was poured into ice-water (1 litre) to produce thehydroxymethyl ketone as a crude solid. This was filtered, washed with alittle water (50 ml.) and recrystallized from aqueous ethanol (charcoal)to give a pale yellow crystalline solid, M.P. 118.

3 amino 1-hydroxy-3-methylbutan-2-one hydrochloride (VI).-The abovephthalimido-ketone (30 g.) was treated 6 N-hydrochloric acid (40 m1.)under reflux for 2 /2 hours. The solution was cooled and phthalic acid(19 g.) which crystallized out was removed by filtration. The filtratewas evaporated to dryness in vacuo, and ethanol (50 ml.) was added,followed by ether (250 ml.) to precipitate the aminoketone ashydrochloride. The product was converted into the semicarbazone, M.P.208, as follows:

Semicarbazide hydrochloride (1 equiv.) was dissolved in the minimum ofwater and sodium bicarbonate (1 equiv.) added with stirring until allefiervescence had ceased. The aminoketone hydrochloride (1 equiv.) wasadded portionwise with stirring and the mixture heated on the steam-bathfor 30 minutes. The aminoketone hydrochloride semicarbazone (VII)separated as a colorless crystalline mass on cooling, and was filtered,then Washed with alcohol and ether, M.P. 208. The compound prepared inthis way pure enough for the subsequent reaction.

2 amino 4 (l,1' dimethyl-3'-hydroxyacetonyl) amino6-hydroxy-S-nitropyrimidine (IX).-The aminoketone hydrochloridesemicarbazone (VII) (6.8 g.), 2-amino-4-chloro-6-hydroxy-5-nitropyrimidine (6.0 g.), and triethylamine(10 ml.) were refluxed in ethanol (450 ml.) for 16-20 hours. Thereaction mixture was cooled and evaporated to 200 ml. to precipitate thepyrimidinylaminoketone semicarbazone (VIII) as a beige solid (6.0 g.),M.P. 206-210. The semicarbazone group was removed by treatment with 2N-hydrochloric acid (100 ml.) under reflux for 10 minutes. The solutionwas cooled, filtered and neutralized with 0.880 ammonia, added dropwisewith stirring, to precipitate the pyri-midinylaminoketone as a yellowwhite solid, which was washed with water, ethanol and ether.

2 amino 4 hydroxy-6-hydroxymethyl-7,7-dirnethyl- 7,8-dihydropteridine(I).--The pyrimidinylaminoketone (4.0 g.) was suspended in water (50ml.), heated on the steam-bath and treated with solid sodium dithioniteuntil the original solid had dissolved. After -10 minutes thedihydropteridine product began to separate out. Heating was continuedfor a further 10 minutes and the mixture was then cooled to complete theseparation of the product, which was filtered and washed with water,ethanol and ether. It was purified by dissolution in 2 N-hydrochloricacid, filtration, and dropwise addition of 0.880 ammonia to pH 8.0 toprecipitate the product. Investigations by 112., UV and NMR, and themobilities on paper chromatog- 4 raphy, all indicated the product hadthe structure of Formula I. The analytical results for the empiricalformula C H N O were:

Element Carbon Hydrogen Nitrogen Theory, percent 48.42 5.87 31.38 Found,percent 48.20 6.27 32.07

N m Tarpon H2N-k N CH:

H CH3 (1) Synthetic Route /0 H2N-:-O-C O OH CH 0 a N-+C O 0H CH4 C 0(II) C 0 CH:

N- h-o 0 C1 CHa oo (m) \N-JIJC O-CHN:

C O O H. (IV) C O CH:

/N- +C O-CHaOH C C O (V) C 0 0H OH I mfi-i z-o o-cmonor- C C 0 OH (VI)(H2N.NH. C 0.NH;

C 01- mfi-d-o-cmon CH; N.NH. CONE; (VII) :T I N02 HNN -Cl NO; N CH:

NH T 1 HN- NH- C0CH OH I \N e m I (X) (VIII) 10 l We claim: 15 1.3-amino-1-hydroxy-3-mcthylbutan-2-0ne.

2. A pharmaceutically acceptable salt of the compound of claim 4.

3. The hydrochloride sa lt of the compound of claim 2.

